foam vs balsa?

Discussion in 'Getting Started' started by zener, Jun 11, 2008.

  1. zener

    zener New Member

    So, I've decided to go with mdf for a base, its particle board like plywood only not warped. Anywho, Now I'm thinking about how to have a river, mountains, grade changes, and rolling terrain to look realistic. My two approach thoughts are:
    1. Use foam as a base and carve out the scenery (dips, canyons and such) and add foam for hills and mountains, if I go this route, I need suggestions on stores online or local where to pick up foam. Home Depot and by association Lowes are eh as they sell foam, but the layers are kinda on the thin side, at least for HO.

    2. Build the rail all on balsa wood. By this, I mean even for the "ground level rail" it would be built upward from the base in an elevated fashion on balsa wood, kinda module style and then I'd have to use some type of covering that would allow for the adding of trees, grass, small structures, I'm not sure what modelers use here.

    3. Some other plan I'm not thinking of.
  2. Squidbait

    Squidbait Recovering ALCO-holic

    Don't do it!!! :excited1:
    MDF is NOT dimensionally stable! :eek:
    It's PAPER! :eek::eek:
    It'll suck up water, change shape with humidity, and isn't strong. :eek::eek::eek:
    What it is is jeezly heavy for the thickness.:v8:

    If you're going to build a tabletop layout, use plywood or OSB or foam.

    Rather than trying to reinvent the wheel, wall1 why don't you read through a few of the layout construction threads here, or look through the beginners section at the NMRA site? They have a good description of how to build a basic 4x8 table from plywood.
  3. steamhead

    steamhead Active Member

    MDF is NOT paper. It's what they call an "engineered" panel. It's by far much more dimensionally stable than plywood. It will not warp under normal usage. The fact that the Architectural Woodworking Institute (AWI) indicates that cabinet doors can only be guaranteed against warpage if MDF or particleboard are used as cores should be an indication of its stability.
    At my place of work we manufacture thousands of cabinets every year...and everyone has either MDF or particleboard cores on the doors.
    I get the idea you're mistaking it for Homasote. THAT is paper....
  4. Squidbait

    Squidbait Recovering ALCO-holic

    You're right.... my bad. :oops:

    But it's still heavy, and I've got several MDF pieces of furniture that managed to wick water up from a basement flood that I wouldn't call dimensionally stable anymore. :p

    In the list of possible layout construction materials, I'd still rank it pretty low considering the alternatives.
  5. MasonJar

    MasonJar It's not rocket surgery

    Sure, MDF is dimensionally stable, but it is not realtively strong in large panels, especially for its weight. A lot of bracing or underlying benchwork will be required.

    Use the foam as the benchwork. You can use 2" foam, set into a 1x4 or 1x5 pine frame, with bracing every two feet (i.e. built in 2x2 foot squares). That is strong and lightweight.

    The foam resists water-based scenicking methods, and can also be carved/shaped. MDF does not, and cannot.

    Balsa is very light, but does not have the strength needed, unless supported by something else. But there are so many other options for "roadbed" that I am not sure why you want to go with balsa...?

  6. steamhead

    steamhead Active Member

    I too do not advice the use of MDF, not because it may warp, but because it IS heavy, and cumbersome to work with. Foam on a "light" structure is probably the best method for your base....
  7. zener

    zener New Member

    So the question that does come to mind is where does one get two inch foam from? Home Depot doesn't carry it, so by definition, Lowes won't either, since they don't know how to stock different variety (yay crappy chain stores) wall1
  8. Squidbait

    Squidbait Recovering ALCO-holic

    Huh. Maybe it has to do with your local climate... up here, both Lowes and HD stock 1/2", 1" and 2" foam. OTOH, as an RC modeller, I'd like to be able to get the 1/4" fan-fold foam, but because of our climate, nobody uses it up here, and I can't get it from anyone local.

    You can use 1", it works fine. If you really want 2" thickness, you can laminate the foam. Any non-solvent glue works well - carpenter's glue, liquid nails, PL etc.
  9. Do a Google search for Austin TX plastics or try plastics supply. Laird Plastics has 1.5" x 48x96 2lb pink foam on their site, they might have other thicknesses in stock.
  10. iis612

    iis612 Member

    Pure genius! That would make a relatively inexpensive roadbed material that is far easier to work than cork.
  11. nachoman

    nachoman Guest

    I will agree with most people here- first and easiest choice is foam. I can find 1 inch here in phoenix at HD in 2x8 foot sheets. You could laminate a few together.

    I recommend staying away from the white beaded stuff, unless you plan on having a flat layout base and do no carving.

    If no suitable foam is available in your area, I recommend the old fashioned method of cookie-cutter plywood or OSB, cork roadbed, over open-frame benchwork and mountains made from plaster over screen.

  12. KentBy

    KentBy GN, NP, SP&S

    Please explain

    I have see information on using foam for senic work, but are you guys laying track on the foam without wood under it?

  13. MasonJar

    MasonJar It's not rocket surgery

  14. zener

    zener New Member

    Ok, I need to do some more reading. Home Depot did have foam that was under 1 inch thick, but I discarded the idea of buying it because I want to do some carving. However, it appears what I should probably should be pursuing is a modular layout setup, using the foam as the base (no carving that foam) and then adding foam or screen stuff on top for scenery. Mason, thanks for the link, that was informative and showed me some of my ignorance.

    I have to agree with KentBy, laying the rr line down on the foam with no wood seems shaky (at least my first impression, which is not always right), especially if that line entails a bridge, which adds weight, but maybe I'm wrong. Also in addition to snagging some xuron tools, I also ordered some layout books, to gather some info and have started to look over the modular forum.
  15. Russ Bellinis

    Russ Bellinis Active Member

    Foam is extremely stiff, but brittle. It will break before it will bend very much. 1/8 inch luan door skin material laminated to the foam with a water based adhesive will strengthen it tremendously. Another foam to consider for making mountains is polyurethane spray foam. It is sold for model railroaders as Mountains in Minutes, but is also available at home centers as spray insulation, and is probably less expensive when bought as insulation from a home center than from Mountains in Minutes.
  16. MasonJar

    MasonJar It's not rocket surgery

    No problem. In fact, with changes to the basic frame, you can create scenery that extends above and below the track. We have some pretty spectacular scenery at (not sure on the current status of the web site, as it is being rebuilt).

    And you don't need to restrict foam construction to modules only. Sure, it's lightweight and (in a 2x4 or 2x6 size) easily portable. But it can be combined with traditional benchwork methods too.

  17. Jim Krause

    Jim Krause Active Member

    I have used cork roadbed, foam roadbed (Woodland Scenics) and no roadbed at all on foam insulation. No problem with any of the three. There is no necessity for balsa or other wood structure under the track if you use insulation foam. I'm currently working on a module that uses one inch by one inch, birch supports with 2 inch foam base. Its very rigid.
    I have also carved grades for a logging railroad directly into foam with good results. Research some of the threads on benchwork. Heavy isn't necessarily better.
  18. CCT70

    CCT70 Member

    I second, third and fourth the recommendation NOT to use MDF. For ANYTHING. I used to work for Sierra Pine in between Amtrak and ST&E and we made the worst of the worst of that crap. It sucks. We used to call it "tree puke". I used to feel dirty making that crap knowing some poor soul was going to pay hard earned money to buy it as furniture and it would eventually degrade and fall apart. I'd lay my track on the ground in the middle of a wet cow pasture before I used MDF on ANYTHING to do with my railroad.

    Just say NO.
  19. MadHatter

    MadHatter Charging at full tilt.

    Remember that one you ballast your track it will, like the real life counter part, hold your track in place.
  20. TrainNut

    TrainNut Ditat Deus

    Not so. That's exactly how my son and I constructed ours and it handles the weight just fine. We're not building houses here, just railroads!:mrgreen:
    Here you can see our benchwork on 12" centers...

    The next shot shows how I laid 1 layer of 1" thick foam on top of the benchwork and I've started laying the cork...

    The final shots shows that the 1, 1" layer of foam is more than adequate in supporting concentrated weight.
    Even after my son jumped back down on the floor, the foam remained intact with no deflection or any sign that my son had been playing up there. If your curious, follow the build of this layout from the ground up, here.

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